Studies

Plasma, the fourth state of matter, is an ionized gas and can be technically produced from gases such as argon, helium, nitrogen, oxygen or air at normal pressure and low temperatures. This "cold atmospheric plasma" (KAP) then consists of a mixture of reactive species such as excited molecules, charged particles, reactive oxygen and nitrogen species and UV radiation. These components contribute to the antimicrobial effect of the plasma, but also mediate effects against parasites, phages and viruses as well as against malignant cells. KAPs can therefore be used to sterilize surfaces, decontaminate food, in dermatology and dentistry. KAPs have also rapidly gained importance as an alternative antiseptic therapy to the use of local antibiotics for non-systemic infections. Due to its versatile mode of action, the development of bacterial resistance to KAP is unlikely.

URL: http://www.thieme-connect.de/DOI/DOI?10.1055/s-0043-112681

Cold atmospheric plasmas (CAP) are used in many medical fields and have developed into a promising medical technology. CAP-generating devices are safe and easy to use and can now be produced cost-effectively thanks to advances in electronics and microchips. One of the main applications of CAP is as a broad-spectrum antimicrobial technology. In view of the high number of infections caused by drug-resistant microorganisms, a non-antibiotic treatment method such as CAP is very promising, especially in the field of wound care. In addition to its antimicrobial properties, CAP treatment improves wound healing by promoting skin microcirculation, monocyte stimulation and keratinocyte proliferation. Dentists use CAP to disinfect teeth, to increase fibroblast activity in the gums and even to whiten teeth. CAP can combat tumor growth by increasing the efficacy of antitumor therapeutics, reactivating apoptotic signaling pathways or downregulating growth-related gene loci. Most health-related research on CAP has been conducted in the last 15 years; the field is relatively young and needs additional research and validation of the existing literature. This report is intended to give the reader an overview of the therapeutic application of cold plasma technology.

Keywords: antimicrobial; cold atmospheric plasma (CAP); therapeutic plasmas; wound treatment.

(Translated from English by DeepL)

URL: https://pubmed.ncbi.nlm.nih.gov/30207843/, last accessed on 22.12.2022

In recent years, plasma medicine has developed into an innovative field of research with great potential. Since the development of low-temperature plasmas, new, multifaceted applications have become available in medicine. A multidisciplinary interest group of physicians, physicists and biologists has been formed who are working together to understand plasma medicine and answer both clinical and scientific questions. New horizons are opening up for dermatology in wound healing, tissue regeneration, the treatment of skin infections and the fight against tumors. However, the greatest challenge in introducing plasma medicine into everyday clinical practice will be to further deepen our knowledge of the precise mechanisms of action of plasma at the cellular level. This is the only way to ensure the safe use of plasma on patients.

The use of cold atmospheric plasma in clinical trials is mainly limited to the treatment of chronic wounds, but its application in a wide range of medical fields is now the target of many analyses. It is therefore likely that its range of applications will be expanded in the future. Cold atmospheric plasma has been shown to reduce microbial load with no known significant adverse effects on healthy tissue, which should enhance its potential application to all microbial infection sites. It has also been shown to have antitumor effects. In addition, it has a proliferative effect on stem cells and other cultured cells, and the greatly increased nitric oxide levels have a very important effect on this proliferation. The use of cold atmospheric plasma can also have a positive effect on immunotherapy in cancer patients. Finally, it is possible that the use of plasma devices will not be limited to surface structures, as current efforts to develop sufficiently small microplasma devices could very likely lead to application in subcutaneous and internal structures. This study summarizes the available literature on the mechanisms of action of cold plasma and analyzes its current in vivo and in vitro applications, particularly in the fields of regenerative medicine, dentistry and oncology.

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7215620/

Background: The development of antibiotic resistance by microorganisms is an increasing problem in medicine. In chronic wounds, bacterial colonization is associated with impaired healing. Cold atmospheric plasma is an innovative promising tool to deal with these problems.

Objectives: The 5-min argon plasma treatment has already demonstrated efficacy in reducing bacterial numbers in chronic infected wounds in vivo. In this study we investigated a 2-min plasma treatment with the same device and the next-generation device, to assess safety and reduction in bacterial load, regardless of the kind of bacteria and their resistance level in chronic wounds.

Methods: Twenty-four patients with chronic infected wounds were treated in a prospective randomized controlled phase II study with 2 min of cold atmospheric argon plasma every day: 14 with MicroPlaSter alpha device, 10 with MicroPlaSter beta device (next-generation device) in addition to standard wound care. The patient acted as his/her own control. Bacterial species were detected by standard bacterial swabs and bacterial load by semiquantitative count on nitrocellulose filters. The plasma settings were the same as in the previous phase II study in which wounds were exposed for 5 min to argon plasma.

Results: Analysis of 70 treatments in 14 patients with the MicroPlaSter alpha device revealed a significant (40%, P<0.016) reduction in bacterial load in plasma-treated wounds, regardless of the species of bacteria. Analysis of 137 treatments in 10 patients with the MicroPlaSter beta device showed a highly significant reduction (23.5%, P<0.008) in bacterial load. No side-effects occurred and the treatment was well tolerated.

Conclusions: A 2-min treatment with either of two cold atmospheric argon plasma devices is a safe, painless and effective technique to decrease the bacterial load in chronic wounds.

The number of periodontitis patients is increasing every year. In addition, more implants were inserted that are affected by peri-implantitis in the same way as periodontitis. Biofilms are the cause of both diseases. There are no satisfactory methods for biofilm removal that also create a surface that promotes wound healing. New treatment methods are therefore needed. In this work, three biofilm models with C. albicans, S. mutans and salivary microorganisms were treated with plasma for 1, 2, 5 and 10 min using three different plasma sources (kINPen09, hollow electrode DBD, volume DBD) and two different gas mixtures (argon and argon+1% O2). Chlorhexidine was carried as a positive control. In addition, various forms of titanium machining (machined, diamond-machined, powder-blasted, etched and blasted) were treated with argon+1%O2 plasma using kINPen09. The element composition, the contact angle and the spread of osteoblast-like MG-63 cells on these surfaces were then determined. SLactive􀂓 was used here as a positive control. In order to test a potential application in periodontology, these tests were also carried out on dentin. All plasma sources and parameters had an antimicrobial effect. The destruction of the cells became clear under the scanning electron microscope. The volume DBD reduced the colony-forming units by around 5 log levels and thus exhibited the highest antimicrobial efficacy. Oxygen addition only led to increased antimicrobial efficacy in the hollow electrode DBD. The plasma treatment reduced the contact angles on all surfaces, in some cases into the superhydrophilic range. EDX analyses showed a reduction in the mass percent of carbon and an increase in the oxygen content of all surfaces after plasma treatment. The proliferation of osteoblasts was significantly higher on the plasma-treated surfaces than on the untreated surfaces and could even exceed the values of the hydrophilic SLactive􀂓 surface. These effects were demonstrated on both titanium and dentin. As plasma has an antimicrobial effect and, as further tests have shown, also removes biofilm, it is suitable for the treatment of peri-implantitis and periodontitis. In addition, the surface becomes more biocompatible, which could promote wound healing. As plasma contains other factors that stimulate wound healing, it represents a promising therapeutic option for the treatment of periodontitis and peri-implantitis in the future.

The aim of this work was to describe the physical characteristics of the DBD plasma source under investigation. In addition, it should be shown for orientation purposes that the plasma source developed and tested in this concept is biocompatible and enables a clinically relevant reduction of bacteria in vitro (RF). For the risk assessment, investigations of the expected UV exposure according to the valid reference (ICNIRP), ex vivo studies with treatment of skin biopsies and in vivo studies on the mouse model were carried out. It could be shown that no damage-relevant UV doses were applied at germ-effective treatment doses with a large therapeutic range and that no microscopic damage occurred in the skin cell layer either ex vivo or in vivo. From this it can be concluded that the characterized and tested DBD plasma source appears to be suitable for the treatment of human skin, which is to be confirmed by further investigations in vitro, ex vivo and in vivo in larger test series. Based on the data, antimicrobial skin treatment can be derived as a potential treatment indication, e.g. MRSA decontamination or the treatment of superficial skin infections.

URL: https://epub.ub.uni-greifswald.de/frontdoor/index/index/year/2012/docId/940

Objective: Antiseptic agents that do not damage the cornea of the eye are usually tolerated by wounds. Therefore, two wound antiseptics were compared with the efficacy and tolerability of tissue tolerable plasma (TTP) on freshly enucleated artificially bacterially contaminated eyes from slaughtered pigs in order to draw conclusions for the use of TTP on wounds. Methods: The removed eyes were transferred to Balanced Salt Solution (BSS), the cornea was contaminated with Staphylococcus aureus or Pseudomonas aeruginosa and incubated for 15 min in an incubator at 37°C. The amount of pathogen was determined by rinsing the cornea with BSS (108 CFU/ml). To test the antiseptic solutions, the corneae were each wetted with 100 !l test solution. After 1 min exposure time for 10% PVP iodine or 10 min for 0.04% polihexanide, the eyes were rinsed with inactivator solution. To test TTP (pulsed mode), the eyes were completely meandered for 58 s at a distance of 5 mm from the plasma pen with the plasma or gas control and then rinsed with BSS. The reduction factors (RF) were calculated from the rinse-off liquids by the difference of the logarithmized pre- and post values. Results: Compared to both test organisms, all types of TTP used were significantly more effective (p <0.001) than the antiseptics tested for comparison (for TTP reduction factor RF 2.4 - 2.9, for the antiseptics RF 1.7 - 2.1). Argon gas (control for TTP) was ineffective, as was BSS (control for the antiseptics). The corneae were not histologically damaged by either the antiseptics or TTP. Conclusion: Due to the identical tolerability of TTP compared to the tested wound antiseptics, the use of TTP on wounds appears possible in principle. The advantage of TTP is not only the higher antiseptic efficacy, but above all the energy supply associated with plasma treatment.

URL: https://epub.ub.uni-greifswald.de/frontdoor/index/index/year/2013/docId/1111

In the last twenty years, fewer and fewer new antibacterial agents have been approved by the US Food and Drug Administration (FDA), while at the same time the resistance situation with multi-resistant bacteria has increased. Community-acquired and nosocomial infections with resistant bacteria have led to a decrease in the effectiveness of standard therapy, an increase in treatment time and an increase in healthcare costs. The aim of this work was therefore to demonstrate the applicability of cold atmospheric plasma for the decolonization of Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus aureus) and Gram-negative bacteria (E. coli) using an ex vivo pig skin model. Freshly collected skin samples from six-month-old female pigs (Pietrain breed) were used. After applying pure bacteria to the surface of the explants, they were treated with cold atmospheric plasma for up to 15 minutes. Two different plasma devices were evaluated. A decolonization efficacy of 3 log10 steps was achieved after only 6 minutes of plasma treatment. Longer plasma treatment times achieved a kill rate of 5 log10 steps regardless of the bacterial strains used. Histologic evaluations of untreated and treated skin areas after treatment with cold atmospheric plasma within 24 hours showed no morphologic changes and no significant degree of necrosis or apoptosis as determined by the TUNEL test, indicating that the porcine skin is still viable. This study shows for the first time that cold atmospheric plasma is able to kill bacteria very efficiently when applied to an intact skin surface. The results underline the potential of cold atmospheric plasma as a new possible treatment option for the decolonization of human skin from bacteria in patients in the future, without damaging the surrounding tissue.

URL: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0034610

URL: Cold plasma therapy in postoperative wound careElektronische Hochschulschriften der LMU Münchenhttps://edoc.ub.uni-muenchen.de ' Sziegoleit_M...

Cold atmospheric plasma is an innovative tool in medicine and hygiene. However, there are no regulations or recommendations for experiments to prove the safety of upcoming devices yet. Healthy ex vivo human skin samples were treated with new upcoming plasma devices (FlatPlaSter 2.0 and MiniFlatPlaSter) for safety purposes. The results indicate-besides the safety measurements/calculations of toxic by-products (O3, NO, and NO2) and the UV power density-that a plasma treatment of up to 2 min is tolerable for the skin (histology and electron microscopy experiments) and safe concerning DNA damages (gamma-H2AX stain assay).

URL: https://www.sciencedirect.com/science/article/abs/pii/S2212816612000029?via%3Dihub

We present the transient, dynamic behavior of ozone production in surface micro-discharge (SMD) plasma in ambient air. Ultraviolet absorption spectroscopy at 254 nm was used to measure the time development of ozone density in a confined volume. We observed that ozone density increases monotonically over 1000 ppm for at least a few minutes when the input power is lower than ∼0.1 W/cm2. Interestingly, when input power is higher than ∼0.1 W/cm2, ozone density starts to decrease in a few tens of seconds at a constant power density, showing a peak ozone density. A model calculation suggests that the ozone depletion at higher power density is caused by quenching reactions with nitrogen oxides that are in turn created by vibrationally excited nitrogen molecules reacting with O atoms. The observed mode transition is significantly different from classical ozone reactors in that the transition takes place over time at a constant power. In addition, we observed a positive correlation between time-averaged ozone density and the inactivation rate of Escherichia coli on adjacent agar plates, suggesting that ozone plays a key role in inactivating bacteria under the conditions considered here.

URL: https://iopscience.iop.org/article/10.1088/1367-2630/14/10/103028

Physical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungus Candida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log(10) CFU reduction on agar plates. C. albicans was the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimental D(23)(°)(C) values for Bacillus subtilis, Bacillus pumilus, Bacillus atrophaeus, and Geobacillus stearothermophilus were determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (D values) are distinctly lower than D values obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma.

URL: https://pubmed.ncbi.nlm.nih.gov/22582068/

In this study we investigated the sensitivity of Deinococcus radiodurans to contact-free cold atmospheric plasma treatment as part of a project to establish new efficient procedures for disinfection of inanimate surfaces. The Gram-positive D. radiodurans is one of the most resistant microorganisms worldwide. Stationary phases of D. radiodurans were exposed to cold atmospheric plasma for different time intervals or to ultraviolet C (UVC) radiation at dose rates of 0.001-0.0656 J cm-², respectively. A methicillin-resistant Staphylococcus aureus strain (MRSA) served as control for Gram-positive bacteria. The surface microdischarge plasma technology was used for generation of cold atmospheric plasma. A plasma discharge was ignited using ambient air. Surprisingly, D. radiodurans was sensitive to the cold atmospheric plasma treatment in the same range as the MRSA strain. Survival of both bacteria decreased with increasing plasma exposure times up to 6 log₁₀ cycles (>99.999 %) within 20 s of plasma treatment. In contrast, UVC radiation of both bacteria demonstrated that D. radiodurans was more resistant to UVC treatment than MRSA. Cold atmospheric plasma seems to be a promising tool for industrial and clinical purposes where time-saving is a critical point to achieve efficient disinfection of inanimate surfaces and where protection from corrosive materials is needed.

URL: https://pubmed.ncbi.nlm.nih.gov/22584820/

Candida albicans is one of the main species able to form a biofilm on almost any surface, causing both skin and superficial mucosal infections. The worldwide increase in antifungal resistance has led to a decrease in the efficacy of standard therapies, prolonging treatment time and increasing health care costs. Therefore, the aim of this work was to demonstrate the applicability of atmospheric plasma at room temperature for inactivating C. albicans growing in biofilms without thermally damaging heat-sensitive materials. This so-called cold atmospheric plasma is produced by applying high voltage to accelerate electrons, which ionize the surrounding air, leading to the production of charged particles, reactive species, and photons. A newly developed plasma device was used, which exhibits a large plasma-generating surface area of 9 by 13 cm (117 cm2). Different time points were selected to achieve an optimum inactivation efficacy range of ≥3 log10 to 5 log10 reduction in CFU per milliliter, and the results were compared with those of 70% ethanol. The results obtained show that contact-free antifungal inactivation of Candida biofilms by cold atmospheric plasma is a promising tool for disinfection of surfaces (and items) in both health care settings and the food industry, where ethanol disinfection should be avoided.

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370520/

Experiments were performed with cold atmospheric plasma (CAP) to inactivate adenovirus, a non-enveloped double stranded DNA virus, in solution. The plasma source used was a surface micro-discharge technology operating in air. Various plasma diagnostic measurements and tests were performed in order to determine the efficacy of CAPs and to understand the inactivation mechanism(s). Different stages of the adenovirus 'life cycle' were investigated-infectivity and gene expression as well as viral replication and spread. Within 240 s of CAP treatment, inactivation of up to 6 decimal log levels can be achieved.

URL: https://iopscience.iop.org/article/10.1088/0022-3727/44/50/505201/meta

In the past few years, cold atmospheric plasma (CAP) has evolved into a new tool in the fight against nosocomial infections and antibiotic-resistant microorganisms. The products generated by the plasma-electrons, ions, reactive species and UV light-represent a 'lethal cocktail' for different kinds of pathogen, which opens up possible applications in hygiene and medicine. Nevertheless, to ensure the safe usage of CAP on skin (e.g., to treat wounds or skin diseases) several pre-clinical in vitro studies have to be performed before implementing clinical trials on humans. In the study presented here, inactivation experiments with Escherichia coli were carried out to identify the necessary plasma dosage for a 5 log reduction: with a small hand-held battery-operated CAP device, these disinfection properties were achieved after application during 30s. This and higher plasma dosages were then used to analyze the mutagenicity induced in V79 Chinese hamster cells-to furthermore define a 'safe application window'-with the HPRT (hypoxanthine-guanine phosphoribosyl transferase) mutation assay. The results show that a CAP treatment of up to 240 s and repeated treatments of 30s every 12h did not induce mutagenicity at the Hprt locus beyond naturally occurring spontaneous mutations.

URL: http://mediatum.ub.tum.de/node?id=1211916&change_language=en

This textbook responds to the growing international need for a practical manual that teaches physicians how to use cold atmospheric pressure plasma (CAP) in everyday patient care. The book introduces readers to the concept of CAP, explains how it works and how safe it is, before describing various diseases and other medical indications for its use. The book then offers guidelines for daily clinical practice, e.g. for the treatment of chronic wounds, the decontamination of infected skin lesions and the inertization of multi-resistant bacteria, as well as a detailed overview of plasma devices. Finally, organizational aspects are addressed that are essential for maintaining and upholding quality standards in the use of cold medical plasma. This textbook offers a unique educational resource and provides relevant information on plasma medicine as an emerging multidisciplinary discipline. Practitioners will appreciate this integrated, comprehensive guide, which is also suitable for advanced medical and dental students and nurses working in plasma-based medical teams.

URL: Textbook of Good Clinical Practice in Cold Plasma TherapySpringerhttps://link.springer.com ' book